Since the Third Industrial Revolution, mechanical arms and robots equipped with a programmable logic controller (PLC) have begun to occupy a pivotal position in the field of industrial production, especially the mechanical arm widely used in precision machining or the IT industry, so that the accuracy of positioning is crucial.
For the mechanical arms, the difficulties of positioning are to overcome various unavoidable errors. The errors can be roughly divided into two kinds: geometric error and non-geometric error. The geometric errors are, for example, the parameter errors of the links of the mechanical arm, the errors between the reference coordinate system and the actual space coordinate system or the parallelism errors of the axes of the joints of the mechanical arm. The most significant non-geometric error is thermal error, followed by backlash error caused by a combination of gears or deformation error of joints and links caused by stress or weight of self-body.
Since the above errors are comprehensively presented on the mechanical arm, it is difficult to establish error compensation models corresponding to various error factors one by one. Even if the error compensation models are established, the individual components of the mechanical arm exist individual errors or different errors caused by component assembly. Therefore, error compensation models are not always adapted to mechanical arms, which make the error compensation work extremely difficult.